The invention bears on the fact that often, particularly in open-hole-completed, sand-screen-provided wells, it is difficult to selectively determine, hence control, the fluid flow paths between the flow pipe of the well and the surrounding rock zones.
This type of control of the fluid flow paths is particularly useful when the flow pipe of the well penetrates rocks of dissimilar flow properties, for example rock zones of dissimilar permeability. In a vertical well, such rock zones may consist of layered rocks. In a horizontal well, lateral variations in the flow properties of the rocks may also exist. Moreover, such variations may exist even when the horizontal portion of the well penetrates one rock type only.
Under such conditions, frequently there is little or no pressure- and fluid communication between adjacent rocks having dissimilar flow properties. Among other things, this may cause uneven fluid drainage of, possibly fluid injection into, said rocks, leading to further known technical disadvantages and problems related to the well, the reservoir and/or the production.
In connection with, for example, petroleum production from a reservoir having zoned rocks of said type(s), it therefore is desirable to undertake successive drainage of individual production zones. Producing as much as possible oil and/or gas from a first reservoir zone, allows this to be carried out. In practice, the production is maintained until the formation water content (water cut) of the outflow assumes a certain maximum limit, after which the first reservoir zone is shut off. The same steps then are carried out for a second reservoir zone, etc.